package com.mobile.framework.util;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Example filter that unconditionally sets the character encoding to be used in
 * parsing the incoming request to a value specified by the
 * <strong>encoding</string> filter initialization parameter in the web app
 * deployment descriptor (</code>/WEB-INF/web.xml</code>). This filter could
 * easily be extended to be more intelligent about what character encoding to
 * set, based on characteristics of the incoming request (such as the values of
 * the <code>Accept-Language</code> and <code>User-Agent</code> headers, or a
 * value stashed in the current user's session).
 */

public class SetCharacterEncodingFilter implements Filter {

	private ThreadBean tb;

	public SetCharacterEncodingFilter() {
		tb = new ThreadBean();
	}

	// ----------------------------------------------------- Instance Variables
	// private final Log log = LogFactory.getLog(getClass().getName());

	/**
	 * The default character encoding to set for requests that pass through this
	 * filter.
	 */
	protected String encoding = null;

	/**
	 * The filter configuration object we are associated with. If this value is
	 * null, this filter instance is not currently configured.
	 */
	protected FilterConfig filterConfig = null;

	// --------------------------------------------------------- Public Methods

	/**
	 * Take this filter out of service.
	 */
	public void destroy() {

		this.encoding = null;
		this.filterConfig = null;

	}

	/**
	 * Select and set (if specified) the character encoding to be used to
	 * interpret request parameters for this request.
	 * 
	 * @param request
	 *            The servlet request we are processing
	 * @param response
	 *            The servlet response we are creating
	 * @param chain
	 *            The filter chain we are processing
	 * 
	 * @exception IOException
	 *                if an input/output error occurs
	 * @exception ServletException
	 *                if a servlet error occurs
	 */
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {

		tb.setContext((HttpServletRequest) request);
		// Select and set (if needed) the character encoding to be used
		String encoding = selectEncoding(request);
		// log.debug("Set request character encode to be " + encoding);
        //System.out.println(encoding);
		if (encoding != null)
			request.setCharacterEncoding(encoding);

		// System.out.println("Enter doFilter......");
		// Pass control on to the next filter
		chain.doFilter(request, response);

		// stop browser caching the page
		HttpServletResponse res = (HttpServletResponse) response;
		res.setHeader("Cache-Control",
				"no-cache,post-check=0,pre-check=0,no-store");
		res.setHeader("Pragma", "no-cache");
		res.setHeader("Expires", "Thu,01Dec199416:00:00GMT");
	}

	/**
	 * Place this filter into service.
	 * 
	 * @param filterConfig
	 *            The filter configuration object
	 */
	public void init(FilterConfig filterConfig) throws ServletException {

		this.filterConfig = filterConfig;
		this.encoding = filterConfig.getInitParameter("encoding");

	}

	// ------------------------------------------------------ Protected Methods

	/**
	 * Select an appropriate character encoding to be used, based on the
	 * characteristics of the current request and/or filter initialization
	 * parameters. If no character encoding should be set, return
	 * <code>null</code>.
	 * <p>
	 * The default implementation unconditionally returns the value configured
	 * by the <strong>encoding</strong> initialization parameter for this
	 * filter.
	 * 
	 * @param request
	 *            The servlet request we are processing
	 */
	protected String selectEncoding(ServletRequest request) {

		return (this.encoding);

	}

}
